Ice Wedge Polygons
Large frost polygons are easily spotted from the air.
Ice wedge polygons are one of the most common ground patterns in the Arctic. Individual polygons range from 5-50 m in diameter and form as the result of winter freezing and spring thawing. At temperatures below -15°C, the soil becomes so brittle that it cracks as it contracts in response to cold temperatures. Come spring, meltwater fills these cracks and subsequently freezes into what are referred to as ice wedges. Year after year, the cracks increase in depth and diameter, and so do the ice wedges. From the air, tundra patterned in this manner resembles a cracked, dried-up mud puddle. The striking geometric appearance of ice wedge polygons dominates the lowlands of arctic Canada.